Despite the ever-growing buzz around the farm-themed Facebook game FarmVille, the game hit a slump last month, dropping from 82 million players in March to 78 million at the end of April.

Inside Social Games, which reported the numbers, attributes this loss to the removal of third-party notifications on Facebook, which mean players stopped receiving a constant flow on what's happening in game. This reasoning seems pretty solid ( Zynga CEO Mark Pincus agrees, telling Business Week that it's only affecting their business in 'the short term'), especially considering that 14 games in the top 25 took a hit last month. That list of games includes Cafe World, Mafia Wars (both from FarmVille creator Zynga), Happy Aquarium from Crowdstar (which was already in decline the previous month), along with Pet Society and Restaurant City from Playfish.

We expect the drop may continue over the next month or so, especially with Facebook's plans to eliminate gift requests from the network, which means that all of the gift giving and receiving will be confined within the game.
It's also hard not to wonder how much of those declining numbers are also a sign of game fatigue, particularly as new games, i.e. Zynga's Treasure Isle, Playfish's Hotel City and Playdom's Social City rocketed into the top 20 games of the month. Serious social gamers have also been actively complaining about bug-riddled games for months, and scores more were teed off last week, after they were required to hand over their email to continue playing FarmVille, Mafia Wars, et al. In a Games.com poll of roughly 500 readers, 61% of the respondents said they would rather quit playing than give up their email. How much of a hold do these games have over its followers if something as simple as giving up an email makes them want to call it quits?

As Facebook continues to lay the smack down on social games that rely on its network to survive, it'll be interesting to see how many of the social gaming companies will be around in the next two years and what big wigs like Zynga and Playfish will do to make sure players keep coming back to spend their real-life cash on virtual goods.